When a wafer produced by a typical semiconductor production process is transported to a facility that performs the next process, the wafer is stored in a wafer carriage (front opening unified POD, hereafter referred to as “FOUP”) and is transported to each process facility through a storage space known as Side Track Buffer (STB) during the transportation.
Since the STB is provided on a rail on the ceiling of the factory that guides the STB, the STB has advantages in that the space usability can be improved and the movement distance between the processes can be shortened.
On the other hand, in the semiconductor production process, yield is a very important factor for measuring the economic efficiency. Incidentally, the reason for a low yield in the semiconductor production process is because the wafer is exposed to oxygen or dust during the process movement, which results in the wafer to be placed in the environment of being contaminated.
Therefore, there has been an effort such that the wafer is not exposed to the contaminated environment throughout the semiconductor production process.